The principal objectives of the proposed research are to determine the electron distributions in molecules and complexes of biological significance, and to correlate the charge densities with the biological activities of the materials. Molecular orbital calculations indicate such correlations, but experimentally-determined charge densities are essential for establishing the true relationships. Nuclear quadrupole resonance (NQR) techniques will be used to detect and measure the nitrogen-14 NQR spectra, and charge densities will be extracted from the measured frequencies. Extension of the NQR studies to oxygen-17 and sulfur-33 will proceed by means of double-resonance techniques, and nuclear magnetic resonance (NMR) studies of N14 will be undertaken. The N14 work will focus on possible correlations of charge densities and biological activities for sulfonamides, barbiturates, phenothiazines, amphetamines, penicillins, and other drugs: the correlations should provide a basis for development of drugs with increased efficacy and decreased side effects. Tumor-inhibiting properties of nitrogen mustards will be correlated with charge distributions determined from N14 and Cl35 NQR spectra. Electron densities in nucleic acid bases, substituted uracils, and amino acids will be determined. Charge-transfer mechanisms will be studied for materials such as phenothiazines and local anesthetics which form charge-transfer complexes. Hydrogen bonding will also be investigated as it relates to biological activity of molecules. Electron distributions and molecular motions will be measured in liquid crystalline materials. The nature of metal-to-nitrogen-ligand bonding will be studied in a variety of annular compounds, or chelates.